Sarthak Tripathy

In Vivo Demonstration of PSMA Expression in Adenocarcinoma Urinary Bladder Using 68Ga-PSMA 11 PET/CT

In vitro and in vivo studies have demonstrated prostate-specific membrane antigen (PSMA) expression in various malignant and benign tumors. Based on the recent immunohistochemical study showing PSMA expression in adenocarcinoma of urinary bladder, we hypothesized that PSMA expression in adenocarcinoma of urinary bladder can be demonstrated in vivo using Ga-PSMA 11 PET/CT. We present a man with exstrophy bladder, presenting with adenocarcinoma urinary bladder referred for staging PET/CT. Both F-FDG and Ga-PSMA-11 PET/CT were done, which showed PSMA expression in the primary tumor as well as metastatic lymph nodes.

Quantitative Assessment of Gynecologic Malignancies

18F-fluorodeoxyglucose PET/CT as a dual-modality imaging, plays a key role in the diagnosis, staging, response assessment, and disease surveillance. Uptake by tumor cells offers an opportunity to differentiate viable malignant cells from posttreatment effects. 18F-fluorodeoxyglucose PET/CT-based criteria have been developed to evaluate treatment response. Uptake can reflect the biologic aggressiveness of the tumor, predicting the risk of metastasis and recurrence. The standardized uptake value can be measured as maximum, mean, or peak. Volumetric uptake measurements have shown substantial promise in providing accurate tumor assessment. We discuss these quantitative parameters in the assessment of gynecologic malignancies.

Formulation and characterization of lutetium-177-labeled stannous (tin) colloid for radiosynovectomy

Objective Easy large-scale production, easy availability, cost-effectiveness, long half-life, and favorable radiation characteristics have made lutetium-177 (177Lu) a preferred radionuclide for use in therapy. Lutetium-177-labeled stannous (177Lu-Sn) colloid particles were formulated for application in radiosynovectomy, followed by in-vitro and in-vivo characterization. Methods Stannous chloride (SnCl2) solution and 177Lu were heated together, the pH was adjusted, and the particles were recovered by centrifugation. The heating time and amount of SnCl2 were varied to optimize the labeling protocol. The labeling efficiency (LE) and radiochemical purity (RCP) of the product were determined. The size and shape of the particles were determined by means of electron microscopy. In-vitro stability was tested in PBS and synovial fluid, and in-vivo stability was tested in humans. Results LE and RCP were greater than 95% and ∼99% (Rf=0–0.1), respectively. Aggregated colloidal particles were spherical (mean size: 241±47 nm). The product was stable in vitro for up to 7 days in PBS as well as in synovial fluid. Injection of the product into the infected knee joint of a patient resulted in its homogenous distribution in the intra-articular space, as seen on the scan. No leakage of activity was seen outside the knee joint even 7 days after injection, indicating good tracer binding and in-vivo stability. Conclusion 177Lu-Sn colloid was successfully prepared with a high LE (>95%) and high RCP (99%) under optimized reaction conditions. Because of the numerous benefits of 177Lu and the ease of preparation of tin colloid particles, 177Lu-Sn colloid particles are significantly superior to its currently available counterparts for use in radiosynovectomy.

Peritoneal super scan on 18F - FDG PET-CT in a patient of burkitt's lymphoma

Peritoneal lymphomatosis is seen less frequently, but when seen, it is mostly associated with aggressive variants of malignancies. FDG uptake has been reported in peritoneal lymphomatosis both in DLBCL and Burkitts lymphoma. We report a case of Burkitts lymphoma with involvement of entire peritoneum, which looks like a “peritoneal super scan” on FDG PET-CT.

Glomus tumor of the larynx: A rare synchronous paraganglioma in a patient with bilateral carotid body tumor detected on 68Ga-DOTANOC PET/CT

Paragangliomas are neoplasms arising from extra-adrenal chromaffin tissue. They frequently cause symptoms by overproduction of catecholamines with known predilection to multicentricity. We describe the case of a patient with bilateral carotid body tumor who underwent a baseline 68 Gallium labeled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-NaI3-Octreotide

18-F-FDG PET-CT in monitoring of chemotherapeutic effect in a case of metastatic hepatic epithelioid hemangioendothelioma

Hepatic epithelioid hemangioendothelioma is a rare variant of mesenchymal tumor. Surgical resection or partial hepatectomy is the treatment of choice in the case of localized disease. However, in metastatic cases, chemotherapeutic drugs targeting the tyrosine kinase are being used. We hereby present 18-F-fludeoxyglucose positron emission tomography-computed tomography findings in a case of a 35-year old woman with metastatic HEHE showing significant response to Sorafenib therapy after 6 months.

Primary germ cell tumor of testes with extensive lymph nodal and splenic metastases masquerading lymphoma on 18-F-FDG PET/CT

Germ cell tumors (GCT) account for the 95% of the malignancies associated with testes. They are the most common solid malignancies affecting the males in the age group of 15–35 years. It is known to be bilateral in 3% of cases. We herein present FDG PET-CT findings of a case with biopsy proven GCT with multiple lymph nodal and splenic metastases mimicking lymphomatous neoplasm.

18-F-FDG PET/CT in localizing additional CNS lesion in a case of langerhans cell histiocytosis: determining accurate extent of the disease

Central nervous system involvement is a rare manifestation of Langerhans cell histiocytosis (LCH), with bone and skin lesions being more frequent. MR remains the investigation of choice for localizing brain lesions. However, due to poor sensitivity of MRI in detecting osseous and pulmonary lesions, it is not used routinely in staging purposes until and unless indicated. We hereby discuss a case of 6-year-old boy of LCH who was referred for 18-F-FDG PET/CT for staging and knowing the extent of the disease, but a lesion in hypothalamus was picked up incidentally on FDG PET-CT study that was confirmed by MRI.

Active Leprosy Neuritis Detected on FDG PET/CT

Uses of FDG PET/CT have been previously documented in multiple series in peripheral nerve pathologies, including neurolymphomatosis, peripheral nerve sheath tumor, and plexopathies. We present the case of a 24-year-old man with leprosy neuritis who underwent FDG PET/CT. We suggest that FDG PET/CT can be used as an adjunct tool to monitor neuritis in leprosy patients.

Incidentally Detected Penile Metastases in a Patient of Carcinoma Urinary Bladder on Follow-up FDG PET/CT

Penis is an extremely uncommon site for metastases to occur and is often associated with very grave prognosis. Most of the secondary tumors originating in the penis have primaries from prostate, urinary bladder, and gastrointestinal tract. We hereby report a 65-year-old man, known case of carcinoma urinary bladder, who came for FDG PET/CT for metastatic workup. PET/CT study revealed FDG-avid mass lesion in the root and shaft of the penis, making it suggestive of metastases, which was confirmed later by MRI correlation.